Wave generating system

ABSTRACT

An improved device for discharging water that is capable of efficiently generating an effective wave-like motion within a body of water. Wave generation devices based on water filled elongated tubular chambers having a substantially closed rear end and a substantially open front end and using compressed air to discharge water, such as the wave cannon, may experience operational inefficiencies from variations in quantities of compressed air. Reducing the quantity of compressed gas may result in ineffective waves and damage to the elongated tube as internal low pressure conditions collapse. A source of make-up fluid configured to mitigate internal low pressure conditions can enable effective wave generation with reduced quantities of compressed air.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. applicationSer. No. 11/786652 filed Apr. 12, 2007, which claims priority to U.S.App. Ser. No. 60/878,784 filed Jan. 6, 2007, both of which are herebyincorporated by reference. This application is also acontinuation-in-part of U.S. application Ser. No. 11/732,233 filed onApr. 3, 2007, which claims priority to U.S. Application Ser. No.60/789,000 filed on Apr. 4, 2006, both of which are also herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a wave generating system. Moreparticularly, the present invention is a wave cannon having improvedefficiency and durability.

BACKGROUND OF THE INVENTION

The wave cannon is a device described in U.S. Pat. No. 5,833,393 toCarnahan et al. ('393 patent), which is hereby incorporated byreference. The wave cannon generally relies on submerged, elongatedchambers (e.g., tubes), which can be effectively or substantially openat one end and substantially closed at the other end.

The wave cannon can create waves by releasing bursts of pressurized airthat force water out of the chamber and into a body of water. Theexpelled water is generally a discrete volume defined by the chamber. Asthe water is forced out of the chamber, it can be used to form a wave.In general, the air follows the expelled water and escapes out theopened end of the water chamber and into the body of water. Water fromthe body of water begins to refill the chamber prior to escape of all ofthe air. Grading of the chamber can improve the escape of air and therefilling of the chamber. Although the '393 patent was primarilydirected to wave generation, alternate applications, such as pumping,are feasible and may be desirable in certain configurations, withmodification to the basic wave generating system.

In practice, it has been found that the '393 patent wave cannon chamberrequires the release of sufficient quantity of pressurized air to expelfully the water in the chamber. That is, a release of air sufficient tocreate a two phase discharge flow, with a large air bubble forcing out aslug of water, has been shown to be effective in generating wave motionin a body of water. However, the volume of pressurized air needed toachieve such effective operation in many embodiments has proven to besomewhat expensive.

However, increasing the volume and/or pressure of the air released hasbeen found in some cases to stratify the air and water in the chamber,so that the air can escape along a portion or annulus of the chamberwithout discharging all of the water from the chamber. Such a partialdischarge of water creates smaller, inferior waves. Of course, a releaseof excess compressed air that produces inferior waves is inefficient.

Reducing the volume and/or pressure of air released has also beendiscovered to be potentially problematic. If the air released isinadequate to discharge fully the water from the chamber, then dependingon the pressure during discharge and that of the surrounding body ofwater, several problems can arise. First, the inadequate discharge ofwater from the chamber can cause inferior or low quality waves. Second,the discharge of water has been observed to be reverse, in some caseshalting the flow outward and rapidly reversing flow direction so as toreturn back to the chamber with a significant impact. When the onceexpelled water returns into the chamber, it creates a suction into themuzzle of the chamber, potentially posing a safety hazard to those inthe wave pool.

Accordingly, it would be useful to have a wave cannon that is capable ofeffectively expelling a volume of water using a lower, economicalquantity of pressurized air, without creating a flow reversal, potentialsafety issue, or an impact against the chamber.

BRIEF SUMMARY OF THE INVENTION

The present invention is a wave cannon that includes a system forimproving efficiency by reducing or mitigating the effect of the lowpressure within the chamber created by expelling water from the chamber.

An aspect of the present invention is that of a device for dischargingwater that is capable of discharging water and generating a wave-likemotion within a body of water. As noted above, this device comprises anelongated tubular chamber having a substantially closed rear end and asubstantially open front end, an anchor securing the chamber below asurface of the body of water and for maintaining the tubular chamber ina desired orientation with respect to the body of water, such that thebody of water is in fluid communication with the tubular chamber via theopen front end, a supply of compressed air fluidly interconnected withthe rear end of the tubular chamber, an air control valve in fluidcommunication with the supply of compressed air for operativelycontrolling the flow of compressed air into the tubular chamber, and asupply of make-up fluid in fluid communication with the rear end of thetubular chamber. Upon actuation of the air control valve, which releasesthe compressed air into the rear end of the tubular chamber to forciblyexpel water within the chamber out of the open front end into the bodyof water, if the chamber reaches a predetermined low pressure after therelease of air into the rear end of the chamber, then the supply ofmake-up fluid introduces fluid into the rear end of the chamber torelieve the low pressure.

The supply of compressed air comprises a compressed air tank fluidlyconnected with an air compressor. The wave generating device as recitedin claim 1, wherein the compressed air tank has a volume at least equalto the volume of the tubular chamber. Optionally, the supply ofcompressed air may be fluidly interconnected with the tubular chamber soas to release compressed air substantially in the direction of the openend.

The predetermined low pressure condition may be any pressure relativelylower than that of the body of water at the open end of the chamber. Thesupply of make-up fluid may introduce fluid into the chamber based onlow pressure within the chamber, with the mass of make-up fluid beingzero for a predetermined low pressure equal to that in the body of waterat the open end of the chamber and increasing as the relatively lowpressure increases with respect to the open end of the chamber.

In an alternative embodiment, the make-up fluid may be gas, such as air,a liquid, such as water, or a mixture of gasses or liquids. The presentinvention may include a fluid control valve within the make-up supplyfor controlling the introduction of make-up fluid into the chamber. Thisvalve may be a check or unidirectional valve.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic overview of an embodiment of the presentinvention.

FIG. 2 is a top view of a wave pool embodiment of the present invention.

FIG. 3 is a schematic side view of an embodiment of the presentinvention

FIG. 4 is a schematic overview of an embodiment of the presentinvention.

FIG. 5 is an axial cutaway view of a chamber of the present invention.

FIG. 6 is an alternate embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a wave generating system. In particular, thepresent invention comprises a wave cannon that includes an additionalsystem for improving efficiency and durability by reducing or mitigatingthe effect of the formation of low pressure within the dischargechamber, which can be created by the expulsion of water from thechamber.

The '393 patent generally disclosed that the volume of the pressurizedair available should be equal to or greater than the combined volume ofair that the elongated water chambers could contain. Col. 2, II. 52-54.In general, the release of compressed air that would discharge or expelall of the water from the chamber would generate an effective wave.However, the '393 patent did not disclose operational issues arisingfrom the release of either too much or too little air into the chamber.

In general, the release of pressurized air creates a high pressurebubble within the rear or substantially closed end of the elongatedchamber; as the bubble expands, it expels the water within the chamberout the substantially open or front end. A side effect of expansion isthat the pressure of the gas or air bubble declines during expansion. Inthe production of effective waves, water is intended to be expelledcompletely from the chamber. Some portion of the air would escape aslarge bubbles out the open end of the chamber into the body of water,while other portions of the air might be dispersed into the body ofwater in a turbulent mix or froth, eventually reducing the pressurewithin the tube as water returned to refill the chamber. Thus, it hadbeen contemplated that a water slug driven by a large volume gas bubbleformed by the released air would produce the most effective discharge ofwater.

As discussed above, compressed air can be costly. However, the releaseof low quantities of pressurized air into the chamber can create adverseeffects beyond that of inferior waves. The release of smaller quantitiesof pressurized air into the chamber can form a bubble that begins theexpulsion of water, but the bubble can then decay to a low pressurecondition within the chamber prior to the full expulsion of water. Thislow pressure can cause water within the chamber and previously expelledwater to reverse direction and re-enter the chamber as the bubblecollapses and air is dispersed. The low pressure bubble can collapseviolently as higher pressure water strikes the rear or substantiallyclosed end of the chamber. In some embodiments, a vacuum exceeding 10bar has been observed. Of course, the resulting impact could damage thechamber, requiring both substantial anchoring of the chamber and the useof “heavy” materials for fabrication of the chamber. See '393 patent,Col. 3, II. 13-18. Further, it has been discovered that the reverse indirection of expelled water creates suction into the chamber from thebody of water, which can be unsafe for individuals swimming or surfingin the vicinity.

An aspect of the present invention is a system for mitigating this lowpressure condition within the discharge chamber, while also enabling thedischarge of sufficient water from the chamber to generate effectivewave motion within the body of water. Preferably, this mitigation may beaccomplished by the introduction of fluid into the elongated chamber toreduce such a low pressure condition and to prevent, or reduce theeffects of, a reverse flow of expelled water. Of course the fluid may beany of a wide variety of liquids and/or gasses, depending upon theapplication. Preferably the fluid is water and/or air when available,for simplicity of design. Preferably also, the location for the make upsource introduction of fluid is at the substantially closed end of thedischarge chamber, also for simplicity of design.

FIG. 1 is an embodiment of the present invention directed to wavegeneration, wherein wave cannon 10 is configured with respect to body ofwater 21, such as wave pool. Make-up 26 is an additional system directedto mitigating low pressure conditions within chamber 7. Line 26L, suchas a pipe, conduit, or hose, of make-up 26 provides a mechanism forwater from make-up source 26S of fluid (i.e., in this case body of water21) to be introduced into the chamber 7 when the pressure within chamber7 drops below a desired setting. For example, make-up 26 could connectto body of water 21 at a particular depth, so that the actuationpressure for introduction of make-up fluid might simply be the waterpressure for the depth at the point of connection. Thus, thepredetermined low pressure may be any pressure in chamber 7 relativelylower than that of the body of water at the connection. Accordingly, insuch cases the mass of fluid introduced by make-up 26 would be zero fora pressure in chamber 7 equal to that in the body of water 21 at theconnection and would increase as the relatively low pressure in chamber7 increases with respect to that at the body of water 21.

This embodiment is thus a wave generating device having an elongatedchamber 7 oriented such that body of water 21 may fill the chamber 7 viaa substantially open front end 7A, a supply of compressed air 2 (i.e.,supported by air compressor 1) fluidly interconnected with chamber 7, anair control valve 5 in fluid communication with the supply of compressedair 2 for controlling the flow of compressed air into chamber 7, amake-up 26 fluidly connected to chamber 7, wherein the air control valve5 can release the compressed air 2 into chamber 7 to expel water withinthe chamber 7 out of the front end 7A and further wherein the make-up 26can introduce water into the chamber 7 to replace at least some of thewater expelled out of the front end 7A. Preferably, but not necessarily,such make-up 26 occurs at substantially closed end 7B.

When pressurized air is released into the chamber 7, pressure withinchamber 7 initially increases. Water within chamber 7 is expelled fromchamber 7 and into body of water 21 along open front end 7A. If a lowpressure is formed within the chamber 7 during this process (e.g., atsubstantially closed end 7B), then water from the make-up 26 would beintroduced into the chamber 7 to mitigate or relieve the low pressurecondition. A check valve 24, or other actuating control valve 25 (notshown) is preferably inserted in make-up 26 in order to control therelease of fluid into chamber 7. Because make-up 26 is directed to flowinto chamber 7, such a valve may be useful for controlling the releaseto a desired low pressure level and to prevent back flow from chamber 7into make-up 26. In an alternative embodiment, such a valve could befluidly connected to atmosphere such that atmospheric air could bereleased into chamber 7 for mitigation of a low pressure condition.

FIG. 2 shows an embodiment in which body of water 21 is configured as awave pool. Waves are generated from chamber 7 in the direction of reef33. Optionally, make-up 26 may draw water from river returns 30 (e.g.,lazy river or action river return) within body of water 21, forintroduction into chamber 7 to mitigate low pressure conditions. Riverreturns 30 may be formed by integrated islands 34 and reef 33 withinwave pool types of body of water 21. For orientation, integrated islands34 are shown with bridges 17 for access. Directional arrows 37 showcurrent flow; this configuration of body of water 21 and make-up 26 willincrease the flow along river returns 30. Surfers may ride river returns30 to travel from the location in body of water 21 where waves break onreef 33 to the point of wave generation near chamber 7. Personnel accesspoints 35 may be provided at the point where make-up 26 draws from riverreturn 30.

Of course, the present invention is not intended to be limited to wavepool applications. In some embodiments, the wave cannon 10 may beadapted for use as a pump or an engine for propulsion of a water basedvehicle. For example, FIG. 3 is a partial schematic of a pumpapplication showing chamber 7. Make-up 26 may collect fluid from a catchbasin, drainage system, or other desired make-up source (not shown).Pressurized air may be released along path 6 in fluid connection withchamber 7 in the direction of arrow 6 d; compressed air 2 expels ordischarges water out the substantially open front end 7A of chamber 7.Also not shown in this figure are the pressurized air source, the airactuating valve, and the configuration of elongated chamber 7 withrespect to body of water 21. Open front end 7A may be submerged or not;if the open front end 7A is not submerged, then the configuration of theelongated chamber 7 may require some structural accommodation, dependingon the application (e.g., optional use of a check valve 24 at open frontend 7A if the wave cannon 10 is used as a pump).

Operation of make-up 26 is similar to that of other embodiments. Uponinitial release of pressurized air into the chamber 7, a high pressurecondition is created and check valve 24 is forced closed. If a lowpressure condition in chamber 7 follows release of the pressurized air,then the check valve 24 will open, permitting the fluid contents ofmake-up 26 to be released into chamber 7 to mitigate or relieve the lowpressure condition. For pumping, make-up 26 may be used for refillingchamber 7. If desired as an option, chamber 7 could also be refilled bywater entering via the open front end 7A of chamber 7, although thatwould counter the intended use as a pump. Because the pressuredifferences will have been reduced, refilling will be by smooth fluidflow.

Thus, the embodiment of FIG. 3 may operate as a pump having an elongatedchamber 7 oriented such that the make-up 26 fluidly connect to chamber 7may be used to fill chamber 7, a supply of compressed air 2 (not shown)fluidly interconnected with the chamber 7, an air control valve 25 (notshown) in fluid communication with the supply of compressed air 2 (notshown) for controlling the flow of compressed air 2 into the chamber 7.An air control valve 25 (not shown) can release the compressed air 2into the chamber 7 to expel water within the chamber 7 out ofsubstantially open front end 7A and make-up 26 can introduce make up 26fluid into the chamber 7 to replace at least some of the water expelledout substantially open front end 7A. Optionally, a water control valve25 in fluid communication with make-up 26 may be used to control theflow of make up 26 water into chamber 7.

It is contemplated that embodiments of the present invention may improvewave cannons used as volume pumps, as shown schematically in FIG. 4.Closed end 7B of chamber 7 may mount check valve 24. Check valve 24 mayvary in size, even to the point of having a diameter equivalent tochamber 7. Thus, check valve 24 may admit or introduce a release offluid from make-up 26 into the chamber 7 in the event of a low pressure.Preferably, but not necessarily for such embodiment, the pressurized airsource release structure, nozzle 6 e within chamber 7, could beconfigured centrally or axially, in-line with the flow within theelongated chamber 7. If the substantially open front end 7A of chamber 7is submerged in a body of water 21, it may further be configured with adischarge check valve 24 permitting discharge only. This configurationof wave cannon 10 could be used as a large volume pump for transferringwater from make-up 26 to body of water 21, as shown in FIG. 4. In such acase, make up source 26S could be a catch basin or drainage collectionpoint, while body of water 21 would be a discharge body.

FIG. 5 is a cross section view of chamber 7 with pressurized air linepath 6 running to axially mounted nozzle 6 e (not shown). Struts 8 maybe used to mount nozzle 6 e (not shown) within the axial orientation.

This arrangement could be modified for use as an in-line flow engine todrive a waterborne vessel, such that the make-up 26 and substantiallyclosed end 7B would face forward and the substantially open end 7A woulddischarge aft. Thus, in general, the present invention contemplates avariety of configurations that embody the principles disclosed herein.

FIG. 6 is an example of an alternative embodiment of the presentinvention wherein make-up 26 draws air from atmosphere into chamber 7 tomitigate a low pressure condition in chamber 7. Make up control valve 25may operate upon reaching a predetermined desired low pressure conditionwithin chamber 7.

Thus, in summary, an aspect of the present invention is that the volumeof compressed or pressurized air released into the chamber 7 may bereduced, depending on the nature of the application, without causing aviolent bubble collapse due to a low pressure condition in the chamber7. The present invention reduces the consumption of compressed orpressurized air (or other gas), which also reduces the operating cost. Afurther aspect of the present invention is that the mitigation of a lowpressure condition within the chamber 7 reduces the tendency of the lowpressure to place a drag on the water expelled from the chamber 7.Accordingly, the present invention enables a reduction of the compressedair used along with little or no decrease in the ability to expel water,and little or no decrease in the quality or effectiveness of wavesgenerated. Further, the invention enables a reduction in the heavinessof materials of construction.

For example, with one embodiment of the present invention, a wave cannondischarge chamber having a cross sectional area of about 4 sq. feet anda length of about 24 feet produced an effective wave using a release ofair about 30-40% the volume as previously required. In fact, this wavecannon was able to generate a 7 foot wave, which had previously onlybeen demonstrated by a release of air sufficient to clear a chamberhaving a cross sectional area of 9.6 sq. feet and a length of 80 feet.

The above examples should be considered to be exemplary embodiments, andare in no way limiting of the present invention. Thus, while thedescription above refers to particular embodiments, it will beunderstood that many modifications may be made without departing fromthe spirit thereof.

1. A device for discharging water capable of generating wave motion in abody of water, said device comprising: an elongated tubular chamberhaving a substantially closed rear end and a substantially open frontend; an anchor securing the chamber below a surface of the body of waterand for maintaining the chamber in a desired orientation with respect tothe body of water, such that the body of water is in fluid communicationwith the chamber via the open front end; a supply of compressed airfluidly interconnected with the rear end of the chamber; and an aircontrol valve in fluid communication with the supply of compressed airfor operatively controlling the flow of compressed air into the chamber,a supply of make-up fluid in fluid communication with the chamber;wherein actuation of the air control valve releases the compressed airinto the rear end of the chamber to forcibly expel water within thechamber out of the open front end into the body of water; and wherein inthe event that the chamber reaches a predetermined low pressure afterthe release of air into the rear end of the chamber, the supply ofmake-up fluid introduces fluid into the rear end of the chamber torelieve the low pressure.
 2. The device according to claim 1, whereinthe supply of make-up fluid is in fluid communication with the rear endof the tubular chamber.
 3. The device according to claim 1, wherein thepredetermined low pressure is any pressure relatively lower than that ofthe body of water at the open end of the chamber.
 4. The deviceaccording to claim 1, wherein the supply of make-up fluid introducesfluid into the chamber based on low pressure in said chamber, the massof make-up fluid being zero for a predetermined low pressure equal tothat in the supply of make-up fluid and increasing as the relative lowpressure increases with respect to that of the supply of make-up fluid.5. The device according to claim 1, wherein the make-up fluid iscomprised of one or more fluids from the group of air and water.
 6. Thedevice according to claim 1, wherein the make-up fluid is an air andwater mixture.
 7. The device according to claim 1, further comprising afluid control valve within the supply of make-up fluid for controllingthe introduction of make-up fluid into the chamber.
 8. The wavegenerating device as recited in claim 1, wherein the supply ofcompressed air comprises a compressed air tank fluidly connected with anair compressor.
 9. The wave generating device as recited in claim 1,wherein the compressed air tank has a volume at least equal to thevolume of the tubular chamber.
 10. The wave generating device as recitedin claim 1, further comprising a fluid control valve within the supplyof make-up fluid for controlling the introduction of make-up fluid intothe chamber, and wherein the fluid control valve is a check valve. 11.The wave generating device as recited in claim 1 wherein the supply ofcompressed air is fluidly interconnected with the tubular chamber andincludes an axially aligned nozzle so as to capable of releasingcompressed air substantially in the direction of the open front end. 12.The device of claim 1, wherein the supply of compressed air is fluidlyinterconnected with the tubular chamber axially and the supply of makeup fluid is fluidly connected to the rear end of the tubular chamber insuch a manner so that actuation of the air control valve releasescompressed air into the rear end of the tubular chamber in the directionof the open front end to forcibly expel water within the chamber out ofthe open front end to generate a wave in the body of water, and in theevent of a formation of a predetermined low pressure within the chamber,the supply of make-up fluid will introduce fluid into the tubularchamber to mitigate the low pressure.
 13. The device according to claim1, wherein the supply of make-up fluid is the body of water.
 14. Thedevice according to claim 1, wherein the body of water is a wave pool.15. The device according to claim 1, wherein the body of water is a wavepool and the supply of make-up fluid is the body of water.
 16. Thedevice according to claim 1, wherein the body of water is a wave poolhaving at least one river return and the supply of make-up fluid is theat least one river return of the body of water.
 17. A device fordischarging water drawn from a make-up supply of water to a body ofwater, said device comprising: an elongated tubular chamber having asubstantially closed rear end and a substantially open front end; ananchor securing the chamber below a surface of the body of water and formaintaining the tubular chamber in a desired orientation with respect tothe body of water, such that the body of water is in fluid communicationwith the tubular chamber via the open front end; a supply of compressedair fluidly interconnected with the rear end of the tubular chamber; andan air control valve in fluid communication with the supply ofcompressed air for operatively controlling the flow of compressed airinto the tubular chamber, a supply of make-up water fluidlyinterconnected with the rear end of the tubular chamber; whereinactuation of the air control valve releases the compressed air into therear end of the tubular chamber to forcibly expel water within thechamber out of the open front end into the body of water; and wherein inthe event that the chamber reaches a predetermined low pressure afterthe release of air into the rear end of the chamber, the supply ofmake-up fluid introduces fluid into the rear end of the chamber torelieve the low pressure and to fill the chamber.
 18. The deviceaccording to claim 17, further comprising a discharge check valve influid communication with the open front end of the chamber and enablingdischarge of the chamber to the body of water but inhibiting reverseflow from the body of water into the chamber along the open front end.